Theory of Time 2024 (Universal Theory for Everything)
BJT..pptx
1. Presented by:
Name- abcd
ID:182- 115- 013
CSE 45th
Presented to
ABCD
Assistant Professor
Department of EEE
Course: CSE131; Basic Electronics Engineering
2. Types of transistor configurations.
Common Base configuration.
Common Emitter configuration.
Common Collector configuration.
Best one.
Alpha , Beta and Gamma.
Advantage & Disadvantage of common
Emitter configuration.
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4. Figure: Common Base Configuration
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This transistor configuration
provides a low input impeden-
ce while offering a high output
impedance.
5. all
ly used
This transistor configuration is probably the
most widely used.
The circuit provides a medium input and
output
impedance levels. Both current and voltage
gain can be described as
medium, but the output is the inverse of the
input, i.e. 180° phase
change. This provides a good over
performance and as such it is
often thought of as the most wide
configuration.
Figure: Common Emitter Configuration
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6. IS ALSO KNOWN AS THE
EMITTER FOLLOWER BECAUSE
THE EMITTER VOLTAGE
FOLLOWS THAT OF THE
BASE. OFFERING A HIGH INPUT
IMPEDANCE AND A LOW
OUTPUT IMPEDANCE IT
• is widely used as a buffer. The voltage gain is
unity, although current gain is high. The
input and output signals are in phase.In view
of these characteristics, the emitter follower
configuration is used as a buffer circuit
providing a high input impedance to prevent
loading of the previous stage, and a low
output impedance to drive following stages.
Figure: Common Collector Configuration
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8. ALPHA (α): It is a large signal current gain in common bas
configuration. It is the ratio of collector current (output current)
to the emitter current (input current).
Beta (β): It is a current gain factor in the common emitter
configuration. It is the ration of collector current (output
current) to base current (output current).
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9. Gamma (γ): It is a current gain in common
collector configuration and It is the ration of
emitter current (output current) to base
current (input current).
It is also called emitter efficiency that how much current is injected
from the emitter to base after recombination of minority charge
carriers in base. It’s value is high compared to α,β.
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ALPHA(Α),BETA(Β) &
GAMMA(Γ)
10. RELATION BETWEEN Α,Β AND
Γ IN A
TRANSISTOR
α,β and γ are the current gain factors in
three CB, CEand CC configurations
respectively.
Relation between α, β and γ :
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11. ICB0 IS THE COLLECTOR TO BASE REVERSE
SATURATION CURRENT.
ICE0 is the collector to emitter reverse
saturation current.
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12. 1)It is used in Audio Amplifiers.
2)It is used in Microphones, Radio, and Music
Players.
3)It is used in Frequency generation circuit to
increase the strength of input signal.
4)It is used to increase the speed of Fans,
Motors, and Timer circuits.
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13. 1)It has a tendency to become noisy with age
especially in moist climate.
2)The voltage gain reduces at low as well as
high frequencies.
3)It provides poor impedance matching and
hence it cannot be used as a final stage of an
amplifier.
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